Irrigation systems are commonly used to compensate for inadequate rainfall by artificially watering turf or other landscape. In their most basic form, irrigation systems comprise water supply lines that direct water to a group of sprinklers. Each sprinkler is placed at varying positions around the landscape, preferably maximizing the area on which water is disbursed.
Control of each sprinkler is typically left to valves coupled to the water supply lines, preventing or allowing water to flow to each of the sprinkler heads. In some residential and commercial irrigation systems, electrically controlled solenoid valves are operatively connected to an irrigation controller or central computer. These irrigation controllers include a microprocessor with an input interface (such as a dial and buttons) where a user can program a desired watering schedule. When the watering schedule calls for irrigation of at least a portion of the landscape, the irrigation controller causes one or more solenoid valves to open so that water flows to their respective sprinklers. When the schedule calls for an end to the irrigation, the irrigation controller causes the solenoid valves to close, stopping the water flow to the sprinklers.
Early irrigation controllers included a fixed number of terminals in which to connect the irrigation system's solenoid valves, as seen in U.S. Pat. No. 5,060,859, the contents of which are hereby incorporated by reference. While functional, these early irrigation controllers lacked the flexibility to connect and control additional valves. Unfortunately, if a user wished to expand their irrigation system, it required either a new irrigation controller with a greater number of valve terminals or the use of multiple irrigation controllers or a second smaller station count controller.
In an effort to increase the flexibility of irrigation controllers, the modular irrigation controller was invented to easily increase the number of sprinklers that can be added to an irrigation system, as seen in U.S. Pat. Nos. 5,956,248; 6,459,959; 6,772,050, the contents of which are hereby incorporated by reference. In a modular irrigation controller, multiple valve leads or irrigation station leads are connected to small modules that removably connect to the controller. Additional station output modules can later be added or removed from the controller as needed.
Prior art modular controllers, however, have numerous drawbacks. For example, older prior art modular controllers typically include modules with a set number of irrigation station terminals. Newer prior art modular controllers increase the number of terminals, but require additional footprint space (e.g., a 4 terminal module may be replaced with a 9 terminal module but requires two module slots.
These prior art modular controllers typically require the modules to be inserted into the controller slots in a specific position order. Further, present day controllers typically do not retain programming information for a module slot after the module is removed.
While sensors such as soil or flow sensors may be added to the prior art modular controllers, these arrangements typically required a separate printed circuit board (PCB) with its own terminal block. These sensors were not in the form of the standard modules and so required mounting and sometimes complicated connections. Further, flow meters required that prior art controllers have some form of two-way communication to read and respond to the flow meter data. Since most prior art controllers lacked such two way communication, personal computers were typically required for such functionality. Typically, controllers on the market with flow sensing capability are considerably more expensive.
In another example, prior art modular controllers are typically produced in either indoor or outdoor models. Outdoor controller models mount a power transformer within the controller housing and must comply with more stringent flame rating guidelines for the entire controller housing materials. By contrast, indoor controller models typically use an external AC wall adapter transformer which has fewer regulation requirements and therefore are significantly less expensive to purchase and implement than external models. Since two distinct irrigation controllers must be used (one indoor and one outdoor) the additional expense of designing and producing two different irrigation controllers is incurred and ultimately passed on to the consumer in the controller purchase price.
What is needed is a modular controller that overcomes the limitations of the prior art. More particularly, a modular controller is needed that can utilize modules with various numbers of irrigation terminals, yet maintain a single slot footprint. A modular controller is also needed that can maximize slot usage by sensor modules, save module programming, and decrease the cost associated with producing both an outdoor and indoor model.